Question


Yeasts capable of leavening bread are widespread, and in the many centuries during which the ancient Egyptians made only unleavened bread, such yeasts must frequently have been mixed into bread doughs accidentally. The Egyptians, however, did not discover leavened bread until about 3000 B. C. That discovery roughly coincided with the introduction of a wheat variety that was preferable to previous varieties because its edible kernel could be removed from the husk without first toasting the grain.

Which of the following, if true, provides the strongest evidence that the two developments were causally related?

(This question is from the Official Guide. Therefore, because of copyrights, the complete question cannot be copied here. The question can be accessed at GMAT Club)

Difficulty: Medium

Accuracy: 76%

Based on: 3657 sessions

Solution


The Story

Yeasts capable of leavening bread are widespread,
Yeasts that can make bread fluffy are common.

and in the many centuries during which the ancient Egyptians made only unleavened bread, such yeasts must frequently have been mixed into bread doughs accidentally.

For many centuries ancient Egyptians made only non-fluffy bread.

During those times, such yeasts must have been added into bread doughs accidentally. 
“must … have been” indicates that this is a speculation. 

How come the author is speculating that such yeasts must frequently have been mixed into bread doughs?
Perhaps because such yeasts are widespread.

Why “accidentally”?
Not certain where the author got this from. Perhaps because the Egyptians made only unleavened bread for many centuries. So maybe ingredients capable of leavening bread were added accidentally. This reasoning could explain the use of the word ‘accidentally’, but I am open to other interpretations as I continue too

How come the bread was unleavened even though yeasts capable of leavening bread were frequently mixed into bread doubts, albeit accidentally?Perhaps something in the baking process caused the yeasts to not make the bread rise. (I understood this idea by relating this portion with the initial part: the phrase ‘yeasts capable of leavening bread’. These yeasts are “capable of leavening bread”. That doesn’t mean that if they are added, bread will rise for sure.)

The Egyptians, however, did not discover leavened bread until about 3000 B. C.
Although yeasts would have been accidentally mixed for quite a while, leavened bread was only discovered later (3000 B. C.). So bread only started rising in around 3000 BC (much later, I presume) for the Egyptians.

That discovery roughly coincided with the introduction of a wheat variety that was preferable to previous varieties because its edible kernel could be removed from the husk without first toasting the grain.
“That discovery” – what discovery? The discovery of fluffy bread
Around the same time that fluffy bread was discovered (3000 BC), a type of wheat was introduced. (Why are they talking about wheat? Ah! The main ingredient of bread.

This type of wheat was preferable to previous types. We’re given a reason for the preference – because the non-edible part (husk) of the grain could be separated without first toasting.(‘edible kernel could be removed from the husk’ —> the husk was probably the non-edible part)

Gist:

  1. Certain yeasts help make bread fluffy.
  2. Such yeasts are very common.
  3. Even though such yeasts must have been accidentally added to bread doughs, for many centuries bread didn’t rise.
  4. The Egyptians started using a new variety of wheat. 
  5. This one did not require toasting of the grain.
  6. Around the same time that the Egyptians started using this new variety of wheat, they discovered fluffy bread

Question Stem


Which of the following, if true, provides the strongest evidence that the two developments were causally related?

What ‘two developments’?

  1. Discovery of leavened bread.
  2. Introduction of the new variety of wheat.

“the two developments were causally related”

So,

  • Either 1 caused 2
  • Or, 2 caused 1

Do both these causal relations make equal sense?

  • The discovery of fluffy bread caused the introduction of new wheat
  • The introduction of the new wheat caused the discovery of fluffy bread

The first relation does not make sense; the latter one does. Right?

Framework: So, after reading the correct answer, I should believe more than I currently do in the notion that the Egyptians discovered fluffy bread because they had started using the new variety of wheat. 

Perhaps the fact that the new wheat variety did not need to be toasted somehow led to the discovery.

Let’s see.

Answer choice analysis


Answer Choice: A

Incorrect

Selected by: 6%

Our job is to look for something that indicates a causal relation between the discovery of leavened bread and the introduction of the new wheat.
This option simply tells us that unleavened bread continued to be popular even after awareness about leavened bread had spread.
It does not help us establish the required causal relation. Irrelevant.


Answer Choice: B

Incorrect

Selected by: 9%

These “stone-lined grain-toasting pits” became available for baking only when they stopped toasting the grain. So, only after they started using the new variety of wheat. 

So, earlier the Egyptians must have used some other pits, or some other form of an oven to bake bread.

This answer choice only talks about a new source of baking becoming available. It does not mention anything about whether this new source had anything to do with the bread becoming fluffy. So, this one is not helpful to establish the causal relation.

Now, what if the answer choice were:

(B’) Stone-lined grain-toasting pits became available for baking bread only after the Egyptians stopped the practice of toasting grain, and bread baked in these pits leavened.

This answer choice would have been correct.

  1. Introduction of the new wheat would have led to stone-lined grain-toasting pits becoming available for breaking bread
  2. Using these pits would have led to bread leavening
  3. That’s how the Egyptians would have discovered leavened bread
  4. So, introduction of the new wheat would have led to the discovery of leavened bread

The original one, however, does not tell us whether the kind of pit in which bread was baked was related to bread becoming fluffy.


Answer Choice: C

Correct

Selected by: 76%

“a protein that must be present for yeast to leaven bread dough.” So, If the protein is not present, the bread will not leaven even if yeast is added.

How is “heating a kernel” relevant?

Oh, the new wheat variety did not require toasting (a form of heating); the old ones did.

The older varieties of wheat had to be heated initially. That would have destroyed their gluten. And that’s why bread wouldn’t have risen, even if there was yeast in the dough.

Now that the grain was not initially toasted, the protein would have remained in the wheat. And perhaps the gluten and the “accidental” yeast would have made the bread rise, leading to the discovery of leavened bread.

This answer choice does give me evidence that using the new variety of wheat led to the discovery of fluffy bread.

.


Answer Choice: D

Incorrect

Selected by: 4%

Who consumed this wheat does not help us establish a causal relation between the introduction of the wheat and the discovery of leavened bread. Irrelevant.


Answer Choice: E

Incorrect

Selected by: 5%

Ok, but did the new wheat lead to the discovery of fluffy bread? All we learn is that flour from the new wheat required less effort to produce. We do not learn anything about how the Egyptians discovered fluffy bread. Irrelevant.

Additional Notes


* Whenever presented with a contrast word: however, but, etc, it is our job to understand what the contrast is. It is not enough to just acknowledge that there is a contrast.

In this passage, when we relate the second statement with the first, we realise that 3000 BC would have to be a time (much?) later than when they used to make only unleavened bread.

  • I have labelled the question as a ‘Strengthen’ question on top. One way to look at the question is that the conclusion is in the question stem (The two events are causally related), and our job is to find evidence to support this. However, remember, at the end of the day, our job is to answer the question that’s been asked on the screen. It doesn’t matter whether we can fit the question into a category. In fact, if you find that by categorising a question you might lose some nuance, it’s better not to categorise.

If you have any doubts regarding any part of this solution, please feel free to ask in the comments section.

Anish Passi

GMAT Coach

With over a decade of GMAT training experience, top 1 percentile scores on the CAT and GMAT, and a passion for teaching, I’d like to believe I am quite qualified to be a GMAT coach. GMAT is learnable, and I help students master the GMAT through a process-oriented approach based on logic and common sense. I offer private tutoring and live-online classroom courses. My sessions are often sprinkled with real-world examples, references to movies, and jokes that only I find funny. You’ve been warned 🙂

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